Unseasonable heat wave spurs call for statewide energy conservation

FOLSOM, Calif. – The California Independent System Operator (ISO) has issued a statewide Flex Alert, a call for voluntary electricity conservation, from 3 p.m. to 10 p.m. today, to prepare for possible energy shortages due to an unusually warm beginning of October.

With high temperatures in the forecast today and tomorrow, the power grid operator is predicting a dramatic rise in electricity demand, primarily from air conditioning use. Power grid operators have been preparing for the hot weather for several days by getting commitments from all available resources.

One of the most important ways the public can help is “pre-cooling” homes and buildings in the morning and early afternoon prior to 3 p.m., and then setting thermostats higher until 10 p.m.

The state’s program for lining up enough energy to serve demand is based on historical weather conditions, which are typically cooling down this time of year. However, the current autumn spike in temperatures – as much as 15-20 degrees above normal — means the grid doesn’t have as much energy available as summer months, when high demand is expected.

In addition to a forecasted capacity shortfall, wildfires are threatening transmission lines across the state, and in fact, generators that were taken offline several weeks ago due to fire have not returned to service. Smoke from wildfires is adding forecast uncertainty, and has the potential to reduce solar power production as the weather pattern changes over the coming days.

Under these circumstances, consumer conservation is needed to absorb any additional unexpected outages on the system. Flex Alert participation today can buffer against reliability concerns and power interruptions.

The ISO was made aware of a projected gap in supply in the day-ahead market yesterday. All available resources were committed to serve load, and steps were taken to bring all resources on line, and to increase flow of imports to the system.

The ISO issued a Grid Alert yesterday to warn of a possible electricity shortage in the day-ahead market, for one hour beginning at 6 p.m. today. A Restricted Maintenance Operations (RMO) notice was also issued for the period of 6 a.m. to 10 p.m. today. The Grid Alert allows operators to access demand response supply, and the RMO allows operators to call all available generation onto the system and bring back transmission that may be offline for planned maintenance.

Consumers are urged to conserve electricity, especially during the late afternoon and early evening, when the grid is most stressed due to higher demand and solar energy production falling.

Energy use reduction during a Flex Alert can prevent further emergency measures, including rotating power outages.

Between 3 p.m. and 10 p.m., the ISO is urging consumers to:

  • Set air conditioning thermostats to 78 degrees, if health permits.
  • Defer use of major appliances.
  • Turn off unnecessary lights.
  • Unplug unused electrical devices.
  • Close blinds and drapes.
  • Use fans when possible.
  • Limit time the refrigerator door is open.

Consumers can also take steps to prepare for the Flex Alert by doing the following before 3 p.m.:

  • “Pre-cool” their homes, or lower air conditioning thermostats.
  • Charge electric vehicles.
  • Charge mobile devices and laptops.
  • Run dishwashers, washing machines and other major appliances.
  • Set pool pumps to run in the early morning or late at night.

While the heat is forecasted to extend into tomorrow and possibly the weekend, no further Flex Alerts have been scheduled at this time. The ISO is closely monitoring supplies, weather and fire activity.

For information on Flex Alerts, to get more electricity conservation tips, and to sign up for conservation alerts, visit the ISO’s Flex Alert websiteVisit the ISO’s News page for more information on the heat wave’s impacts on grid operations, and to learn more about alerts, warnings and emergency notices.

For updates on grid operations, follow us on Twitter at @California_ISO or @FlexAlert, or monitor system conditions in real time at ISO’s Today’s Outlook.

Alyson Hanner

Alyson Hanner joined the California Governor's Office of Emergency Services (Cal OES) in 2020 after working nearly 20 years in the broadcast news industry. Since joining Cal OES, she has assisted in the response and recovery efforts of the historic 2020 wildfires and the COVID-19 pandemic. Previously, she served as managing editor at local television stations in San Diego and Sacramento.

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